Polyclinum marsupiale Kott, 1963

Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), Journal of Natural History 40 (3 - 4), pp. 169-234 : 194-195

Polyclinum marsupiale Kott, 1963

( Figure 9E )

Polyclinum marsupiale Kott 1963, p 83 ; 1992a, p 452 and synonymy.

Distribution

Previously recorded (see Kott 1992a): Western Australia (Rottnest I., Albany) ; South Australia (Kingston, Victor Harbour); Victoria (Portland, Deal I.); Tasmania (Hunter I.). New record : South Australia (Kangaroo I., SAM E2866–7 , E3298 ) .

Description

Sandy, more or less circular cushions with rounded margins are fixed to the substratum by most of the under surface, although one specimen ( SAM E2867 ) has an extension of part of the under surface attached to a bryozoan skeleton that holds the circular plate-like colony aloft, like a mushroom. Elevations, each containing a circle of zooids around a terminal cylindrical common cloacal aperture, project from the upper surface. The test is colourless and brown zooids are visible through it. Sand is only sparse in the internal test. A long narrow atrial lip from the body wall anterior to the small circular atrial aperture of each zooid is inserted into the test around each common cloacal aperture. The atrial lip has a straight or a pointed tip, or it is produced into a fringe of four or five pointed lobes or up to 10 minute denticulations. A small post-atrial papillum projects from the body wall just behind the atrial aperture. About 16 rows of stigmata have about 15 stigmata per half row and about the same number of flat branchial papillae on each transverse vessel. The stomach is small and smooth-walled; the gonads are in a sac constricted off from the abdomen. The proximal part of the vas deferens runs a convoluted course over the surface of the gonads and it may straighten out as the gonads mature. Embryos are crowded in a brood pouch protruding from the thorax behind the atrial cavity in the newly recorded specimens ( SAM E3298 collected in November) .

Remarks

The specimens are consistent with those described previously for this temperate species. It is distinguished from Polyclinum incrustatum by its brown zooids, presence of a brood pouch constricted off from the thorax, fewer rows of stigmata and cloacal systems that consist of a simple circle of zooids around a protruberant common cloacal aperture.

Figures

Figure 9. In situ images of: (A) Pseudodistoma gracile (SAM E3270); (B) Pseudodistoma inflatum (SAM E3297); (C) Pseudodistoma pilatum (SAM E3296); (D) Polyclinum incrustatum (SAM E3274); (E) Polyclinum marsupiale (SAM E2866); (F) Aplidiopsis confluata (SAM E3281); (G) Aplidiopsis confluata (SAM E3282); (H) Synoicum citrum (SAM E3277).